(Revised)Database Design Question, Header With Two Detail.. Pls Help

Hi All,
There is some additional info I forget on this same topic I just posted.

I have a database design question, pls give me some help..

I want to define tables for salesman's sales target commission . The
commission could be given per EITHER sales amount of : Group of Products OR
Group of Brand. e.g : the data example :
For one salesman_A :
product_1, product_2, product_3 etc.. => sales = $100 - $200 =>
commission = 5%
product_1, product_2, product_3 etc.. => sales = $201 - $400 =>
commission = 10%
Brand_A, Brand_B, Brand_C .. etc => sales = $100 - $200 =>
commission = 2.5%
Brand_A, Brand_B, Brand_C .. etc => sales = $201 - $400 =>
commission = 5%

Below is my table design, is this a good design or something is wrong here ?
Thank you for your help.

CREATE TABLE Sales_Commission_Header (
Sales_ID Char(4) ,
Sales_Commission_Group Char(4),
Note Varchar(30),
Constraint Sales_Commission_Header_PK Primary Key(Sales_ID,
Sales_Commission_Group)
)
Alter Table Sales_Commission_Header Add Constraint
FK_Sales_Commission_Header Foreign Key (Sales_Commission_Group)
References Commission_Group_Header(Sales_Commission_Group)

CREATE TABLE Sales_Commission_Detail (
Sales_ID Char(4) ,
Sales_Commission_Group Char(4),
Sales_From Decimal(12,2) ,
Sales_To Decimal(12,2) ,
Commission Decimal(5,2),
Constraint Sales_Commission_Detail_PK Primary Key(Sales_ID,
Sales_Commission_Group, Sales_From, Sales_To)
)
Alter Table Sales_Commission_Detail Add Constraint FK_Sales_Commission
Foreign Key (Sales_ID, Sales_Commission_Group) References
Sales_Commission_Header(Sales_ID, Sales_Commission_Group)

--------------------------------------------

** ALTERNATIVE _1 :

CREATE TABLE Commission_Group_Header (
Sales_Commission_Group Char(4) Primary Key,
Note Varchar(30)
)

CREATE TABLE Commission_Group_Detail_Product (
Sales_Commission_Group Char(4),
Product_ID VarChar(10), -- This product_ID will be FK
reference to master product
Constraint Commission_Group_Detail_Product_PK Primary
Key(Sales_Commission_Group, Product_ID)
)
Alter Table Commission_Group_Detail_Product Add Constraint
FK_Commission_Group_Detail_Product Foreign Key (Sales_Commission_Group)
References Commission_Group_Header(Sales_Commission_Group)

CREATE TABLE Commission_Group_Detail_Brand (
Sales_Commission_Group Char(4),
Brand_ID VarChar(10), -- This brand_ID will be FK
reference to master brand
Constraint Commission_Group_Detail_Brand_PK Primary
Key(Sales_Commission_Group, Brand_ID)
)
Alter Table Commission_Group_Detail_Brand Add Constraint
FK_Commission_Group_Detail_Brans Foreign Key (Sales_Commission_Group)
References Commission_Group_Header(Sales_Commission_Group)

** ALTERNATIVE _2 :

CREATE TABLE Commission_Group_Header (
Sales_Commission_Group Char(4),
Group_Type Char(1), -- 'B': Brand Group 'P': Product Group
Note Varchar(30),
Constraint Commission_Group_Header_PK Primary Key(Sales_Commission_Group,
Group_Type)
)

CREATE TABLE Commission_Group_Detail (
Sales_Commission_Group Char(4),
Group_Type Char(1), -- 'B': Brand Group 'P': Product Group
Product_Brand_ID VarChar(10),
Constraint Commission_Group_Detail_PK Primary Key(Sales_Commission_Group,
Group_Type, Product_Brand_ID)
)
Alter Table Commission_Group_Detail Add Constraint
FK_Commission_Group_Detail Foreign Key (Sales_Commission_Group)
References Commission_Group_Header(Sales_Commission_Group, Group_Type)

The PROBLEM here is : with Product_Brand_ID , I CAN NOT make foreign key
into both Master Product and Master Brand.

So which one is better design ?
split the Commission_Group_Detail into Two tables, product and brand , and
make the FOREIGN KEY
to master product and master brand (previous mail)
OR
combile Commission_Group_Detail for Product and Brand into one table like
above
and NOT make any FK to master Product or Brand ?


Thank you for your help,
Tristant